1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /* General filesystem caching interface
3 *
4 * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 *
7 * NOTE!!! See:
8 *
9 * Documentation/filesystems/caching/netfs-api.txt
10 *
11 * for a description of the network filesystem interface declared here.
12 */
13
14 #ifndef _LINUX_FSCACHE_H
15 #define _LINUX_FSCACHE_H
16
17 #include <linux/fs.h>
18 #include <linux/list.h>
19 #include <linux/pagemap.h>
20 #include <linux/pagevec.h>
21 #include <linux/list_bl.h>
22
23 #if defined(CONFIG_FSCACHE) || defined(CONFIG_FSCACHE_MODULE)
24 #define fscache_available() (1)
25 #define fscache_cookie_valid(cookie) (cookie)
26 #else
27 #define fscache_available() (0)
28 #define fscache_cookie_valid(cookie) (0)
29 #endif
30
31
32 /*
33 * overload PG_private_2 to give us PG_fscache - this is used to indicate that
34 * a page is currently backed by a local disk cache
35 */
36 #define PageFsCache(page) PagePrivate2((page))
37 #define SetPageFsCache(page) SetPagePrivate2((page))
38 #define ClearPageFsCache(page) ClearPagePrivate2((page))
39 #define TestSetPageFsCache(page) TestSetPagePrivate2((page))
40 #define TestClearPageFsCache(page) TestClearPagePrivate2((page))
41
42 /* pattern used to fill dead space in an index entry */
43 #define FSCACHE_INDEX_DEADFILL_PATTERN 0x79
44
45 struct pagevec;
46 struct fscache_cache_tag;
47 struct fscache_cookie;
48 struct fscache_netfs;
49
50 typedef void (*fscache_rw_complete_t)(struct page *page,
51 void *context,
52 int error);
53
54 /* result of index entry consultation */
55 enum fscache_checkaux {
56 FSCACHE_CHECKAUX_OKAY, /* entry okay as is */
57 FSCACHE_CHECKAUX_NEEDS_UPDATE, /* entry requires update */
58 FSCACHE_CHECKAUX_OBSOLETE, /* entry requires deletion */
59 };
60
61 /*
62 * fscache cookie definition
63 */
64 struct fscache_cookie_def {
65 /* name of cookie type */
66 char name[16];
67
68 /* cookie type */
69 uint8_t type;
70 #define FSCACHE_COOKIE_TYPE_INDEX 0
71 #define FSCACHE_COOKIE_TYPE_DATAFILE 1
72
73 /* select the cache into which to insert an entry in this index
74 * - optional
75 * - should return a cache identifier or NULL to cause the cache to be
76 * inherited from the parent if possible or the first cache picked
77 * for a non-index file if not
78 */
79 struct fscache_cache_tag *(*select_cache)(
80 const void *parent_netfs_data,
81 const void *cookie_netfs_data);
82
83 /* consult the netfs about the state of an object
84 * - this function can be absent if the index carries no state data
85 * - the netfs data from the cookie being used as the target is
86 * presented, as is the auxiliary data and the object size
87 */
88 enum fscache_checkaux (*check_aux)(void *cookie_netfs_data,
89 const void *data,
90 uint16_t datalen,
91 loff_t object_size);
92
93 /* get an extra reference on a read context
94 * - this function can be absent if the completion function doesn't
95 * require a context
96 */
97 void (*get_context)(void *cookie_netfs_data, void *context);
98
99 /* release an extra reference on a read context
100 * - this function can be absent if the completion function doesn't
101 * require a context
102 */
103 void (*put_context)(void *cookie_netfs_data, void *context);
104
105 /* indicate page that now have cache metadata retained
106 * - this function should mark the specified page as now being cached
107 * - the page will have been marked with PG_fscache before this is
108 * called, so this is optional
109 */
110 void (*mark_page_cached)(void *cookie_netfs_data,
111 struct address_space *mapping,
112 struct page *page);
113 };
114
115 /*
116 * fscache cached network filesystem type
117 * - name, version and ops must be filled in before registration
118 * - all other fields will be set during registration
119 */
120 struct fscache_netfs {
121 uint32_t version; /* indexing version */
122 const char *name; /* filesystem name */
123 struct fscache_cookie *primary_index;
124 };
125
126 /*
127 * data file or index object cookie
128 * - a file will only appear in one cache
129 * - a request to cache a file may or may not be honoured, subject to
130 * constraints such as disk space
131 * - indices are created on disk just-in-time
132 */
133 struct fscache_cookie {
134 atomic_t usage; /* number of users of this cookie */
135 atomic_t n_children; /* number of children of this cookie */
136 atomic_t n_active; /* number of active users of netfs ptrs */
137 spinlock_t lock;
138 spinlock_t stores_lock; /* lock on page store tree */
139 struct hlist_head backing_objects; /* object(s) backing this file/index */
140 const struct fscache_cookie_def *def; /* definition */
141 struct fscache_cookie *parent; /* parent of this entry */
142 struct hlist_bl_node hash_link; /* Link in hash table */
143 void *netfs_data; /* back pointer to netfs */
144 struct radix_tree_root stores; /* pages to be stored on this cookie */
145 #define FSCACHE_COOKIE_PENDING_TAG 0 /* pages tag: pending write to cache */
146 #define FSCACHE_COOKIE_STORING_TAG 1 /* pages tag: writing to cache */
147
148 unsigned long flags;
149 #define FSCACHE_COOKIE_LOOKING_UP 0 /* T if non-index cookie being looked up still */
150 #define FSCACHE_COOKIE_NO_DATA_YET 1 /* T if new object with no cached data yet */
151 #define FSCACHE_COOKIE_UNAVAILABLE 2 /* T if cookie is unavailable (error, etc) */
152 #define FSCACHE_COOKIE_INVALIDATING 3 /* T if cookie is being invalidated */
153 #define FSCACHE_COOKIE_RELINQUISHED 4 /* T if cookie has been relinquished */
154 #define FSCACHE_COOKIE_ENABLED 5 /* T if cookie is enabled */
155 #define FSCACHE_COOKIE_ENABLEMENT_LOCK 6 /* T if cookie is being en/disabled */
156 #define FSCACHE_COOKIE_AUX_UPDATED 8 /* T if the auxiliary data was updated */
157 #define FSCACHE_COOKIE_ACQUIRED 9 /* T if cookie is in use */
158 #define FSCACHE_COOKIE_RELINQUISHING 10 /* T if cookie is being relinquished */
159
160 u8 type; /* Type of object */
161 u8 key_len; /* Length of index key */
162 u8 aux_len; /* Length of auxiliary data */
163 u32 key_hash; /* Hash of parent, type, key, len */
164 union {
165 void *key; /* Index key */
166 u8 inline_key[16]; /* - If the key is short enough */
167 };
168 union {
169 void *aux; /* Auxiliary data */
170 u8 inline_aux[8]; /* - If the aux data is short enough */
171 };
172 };
173
174 static inline bool fscache_cookie_enabled(struct fscache_cookie *cookie)
175 {
176 return test_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
177 }
178
179 /*
180 * slow-path functions for when there is actually caching available, and the
181 * netfs does actually have a valid token
182 * - these are not to be called directly
183 * - these are undefined symbols when FS-Cache is not configured and the
184 * optimiser takes care of not using them
185 */
186 extern int __fscache_register_netfs(struct fscache_netfs *);
187 extern void __fscache_unregister_netfs(struct fscache_netfs *);
188 extern struct fscache_cache_tag *__fscache_lookup_cache_tag(const char *);
189 extern void __fscache_release_cache_tag(struct fscache_cache_tag *);
190
191 extern struct fscache_cookie *__fscache_acquire_cookie(
192 struct fscache_cookie *,
193 const struct fscache_cookie_def *,
194 const void *, size_t,
195 const void *, size_t,
196 void *, loff_t, bool);
197 extern void __fscache_relinquish_cookie(struct fscache_cookie *, const void *, bool);
198 extern int __fscache_check_consistency(struct fscache_cookie *, const void *);
199 extern void __fscache_update_cookie(struct fscache_cookie *, const void *);
200 extern int __fscache_attr_changed(struct fscache_cookie *);
201 extern void __fscache_invalidate(struct fscache_cookie *);
202 extern void __fscache_wait_on_invalidate(struct fscache_cookie *);
203 extern int __fscache_read_or_alloc_page(struct fscache_cookie *,
204 struct page *,
205 fscache_rw_complete_t,
206 void *,
207 gfp_t);
208 extern int __fscache_read_or_alloc_pages(struct fscache_cookie *,
209 struct address_space *,
210 struct list_head *,
211 unsigned *,
212 fscache_rw_complete_t,
213 void *,
214 gfp_t);
215 extern int __fscache_alloc_page(struct fscache_cookie *, struct page *, gfp_t);
216 extern int __fscache_write_page(struct fscache_cookie *, struct page *, loff_t, gfp_t);
217 extern void __fscache_uncache_page(struct fscache_cookie *, struct page *);
218 extern bool __fscache_check_page_write(struct fscache_cookie *, struct page *);
219 extern void __fscache_wait_on_page_write(struct fscache_cookie *, struct page *);
220 extern bool __fscache_maybe_release_page(struct fscache_cookie *, struct page *,
221 gfp_t);
222 extern void __fscache_uncache_all_inode_pages(struct fscache_cookie *,
223 struct inode *);
224 extern void __fscache_readpages_cancel(struct fscache_cookie *cookie,
225 struct list_head *pages);
226 extern void __fscache_disable_cookie(struct fscache_cookie *, const void *, bool);
227 extern void __fscache_enable_cookie(struct fscache_cookie *, const void *, loff_t,
228 bool (*)(void *), void *);
229
230 /**
231 * fscache_register_netfs - Register a filesystem as desiring caching services
232 * @netfs: The description of the filesystem
233 *
234 * Register a filesystem as desiring caching services if they're available.
235 *
236 * See Documentation/filesystems/caching/netfs-api.txt for a complete
237 * description.
238 */
239 static inline
240 int fscache_register_netfs(struct fscache_netfs *netfs)
241 {
242 if (fscache_available())
243 return __fscache_register_netfs(netfs);
244 else
245 return 0;
246 }
247
248 /**
249 * fscache_unregister_netfs - Indicate that a filesystem no longer desires
250 * caching services
251 * @netfs: The description of the filesystem
252 *
253 * Indicate that a filesystem no longer desires caching services for the
254 * moment.
255 *
256 * See Documentation/filesystems/caching/netfs-api.txt for a complete
257 * description.
258 */
259 static inline
260 void fscache_unregister_netfs(struct fscache_netfs *netfs)
261 {
262 if (fscache_available())
263 __fscache_unregister_netfs(netfs);
264 }
265
266 /**
267 * fscache_lookup_cache_tag - Look up a cache tag
268 * @name: The name of the tag to search for
269 *
270 * Acquire a specific cache referral tag that can be used to select a specific
271 * cache in which to cache an index.
272 *
273 * See Documentation/filesystems/caching/netfs-api.txt for a complete
274 * description.
275 */
276 static inline
277 struct fscache_cache_tag *fscache_lookup_cache_tag(const char *name)
278 {
279 if (fscache_available())
280 return __fscache_lookup_cache_tag(name);
281 else
282 return NULL;
283 }
284
285 /**
286 * fscache_release_cache_tag - Release a cache tag
287 * @tag: The tag to release
288 *
289 * Release a reference to a cache referral tag previously looked up.
290 *
291 * See Documentation/filesystems/caching/netfs-api.txt for a complete
292 * description.
293 */
294 static inline
295 void fscache_release_cache_tag(struct fscache_cache_tag *tag)
296 {
297 if (fscache_available())
298 __fscache_release_cache_tag(tag);
299 }
300
301 /**
302 * fscache_acquire_cookie - Acquire a cookie to represent a cache object
303 * @parent: The cookie that's to be the parent of this one
304 * @def: A description of the cache object, including callback operations
305 * @index_key: The index key for this cookie
306 * @index_key_len: Size of the index key
307 * @aux_data: The auxiliary data for the cookie (may be NULL)
308 * @aux_data_len: Size of the auxiliary data buffer
309 * @netfs_data: An arbitrary piece of data to be kept in the cookie to
310 * represent the cache object to the netfs
311 * @object_size: The initial size of object
312 * @enable: Whether or not to enable a data cookie immediately
313 *
314 * This function is used to inform FS-Cache about part of an index hierarchy
315 * that can be used to locate files. This is done by requesting a cookie for
316 * each index in the path to the file.
317 *
318 * See Documentation/filesystems/caching/netfs-api.txt for a complete
319 * description.
320 */
321 static inline
322 struct fscache_cookie *fscache_acquire_cookie(
323 struct fscache_cookie *parent,
324 const struct fscache_cookie_def *def,
325 const void *index_key,
326 size_t index_key_len,
327 const void *aux_data,
328 size_t aux_data_len,
329 void *netfs_data,
330 loff_t object_size,
331 bool enable)
332 {
333 if (fscache_cookie_valid(parent) && fscache_cookie_enabled(parent))
334 return __fscache_acquire_cookie(parent, def,
335 index_key, index_key_len,
336 aux_data, aux_data_len,
337 netfs_data, object_size, enable);
338 else
339 return NULL;
340 }
341
342 /**
343 * fscache_relinquish_cookie - Return the cookie to the cache, maybe discarding
344 * it
345 * @cookie: The cookie being returned
346 * @aux_data: The updated auxiliary data for the cookie (may be NULL)
347 * @retire: True if the cache object the cookie represents is to be discarded
348 *
349 * This function returns a cookie to the cache, forcibly discarding the
350 * associated cache object if retire is set to true. The opportunity is
351 * provided to update the auxiliary data in the cache before the object is
352 * disconnected.
353 *
354 * See Documentation/filesystems/caching/netfs-api.txt for a complete
355 * description.
356 */
357 static inline
358 void fscache_relinquish_cookie(struct fscache_cookie *cookie,
359 const void *aux_data,
360 bool retire)
361 {
362 if (fscache_cookie_valid(cookie))
363 __fscache_relinquish_cookie(cookie, aux_data, retire);
364 }
365
366 /**
367 * fscache_check_consistency - Request validation of a cache's auxiliary data
368 * @cookie: The cookie representing the cache object
369 * @aux_data: The updated auxiliary data for the cookie (may be NULL)
370 *
371 * Request an consistency check from fscache, which passes the request to the
372 * backing cache. The auxiliary data on the cookie will be updated first if
373 * @aux_data is set.
374 *
375 * Returns 0 if consistent and -ESTALE if inconsistent. May also
376 * return -ENOMEM and -ERESTARTSYS.
377 */
378 static inline
379 int fscache_check_consistency(struct fscache_cookie *cookie,
380 const void *aux_data)
381 {
382 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
383 return __fscache_check_consistency(cookie, aux_data);
384 else
385 return 0;
386 }
387
388 /**
389 * fscache_update_cookie - Request that a cache object be updated
390 * @cookie: The cookie representing the cache object
391 * @aux_data: The updated auxiliary data for the cookie (may be NULL)
392 *
393 * Request an update of the index data for the cache object associated with the
394 * cookie. The auxiliary data on the cookie will be updated first if @aux_data
395 * is set.
396 *
397 * See Documentation/filesystems/caching/netfs-api.txt for a complete
398 * description.
399 */
400 static inline
401 void fscache_update_cookie(struct fscache_cookie *cookie, const void *aux_data)
402 {
403 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
404 __fscache_update_cookie(cookie, aux_data);
405 }
406
407 /**
408 * fscache_pin_cookie - Pin a data-storage cache object in its cache
409 * @cookie: The cookie representing the cache object
410 *
411 * Permit data-storage cache objects to be pinned in the cache.
412 *
413 * See Documentation/filesystems/caching/netfs-api.txt for a complete
414 * description.
415 */
416 static inline
417 int fscache_pin_cookie(struct fscache_cookie *cookie)
418 {
419 return -ENOBUFS;
420 }
421
422 /**
423 * fscache_pin_cookie - Unpin a data-storage cache object in its cache
424 * @cookie: The cookie representing the cache object
425 *
426 * Permit data-storage cache objects to be unpinned from the cache.
427 *
428 * See Documentation/filesystems/caching/netfs-api.txt for a complete
429 * description.
430 */
431 static inline
432 void fscache_unpin_cookie(struct fscache_cookie *cookie)
433 {
434 }
435
436 /**
437 * fscache_attr_changed - Notify cache that an object's attributes changed
438 * @cookie: The cookie representing the cache object
439 *
440 * Send a notification to the cache indicating that an object's attributes have
441 * changed. This includes the data size. These attributes will be obtained
442 * through the get_attr() cookie definition op.
443 *
444 * See Documentation/filesystems/caching/netfs-api.txt for a complete
445 * description.
446 */
447 static inline
448 int fscache_attr_changed(struct fscache_cookie *cookie)
449 {
450 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
451 return __fscache_attr_changed(cookie);
452 else
453 return -ENOBUFS;
454 }
455
456 /**
457 * fscache_invalidate - Notify cache that an object needs invalidation
458 * @cookie: The cookie representing the cache object
459 *
460 * Notify the cache that an object is needs to be invalidated and that it
461 * should abort any retrievals or stores it is doing on the cache. The object
462 * is then marked non-caching until such time as the invalidation is complete.
463 *
464 * This can be called with spinlocks held.
465 *
466 * See Documentation/filesystems/caching/netfs-api.txt for a complete
467 * description.
468 */
469 static inline
470 void fscache_invalidate(struct fscache_cookie *cookie)
471 {
472 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
473 __fscache_invalidate(cookie);
474 }
475
476 /**
477 * fscache_wait_on_invalidate - Wait for invalidation to complete
478 * @cookie: The cookie representing the cache object
479 *
480 * Wait for the invalidation of an object to complete.
481 *
482 * See Documentation/filesystems/caching/netfs-api.txt for a complete
483 * description.
484 */
485 static inline
486 void fscache_wait_on_invalidate(struct fscache_cookie *cookie)
487 {
488 if (fscache_cookie_valid(cookie))
489 __fscache_wait_on_invalidate(cookie);
490 }
491
492 /**
493 * fscache_reserve_space - Reserve data space for a cached object
494 * @cookie: The cookie representing the cache object
495 * @i_size: The amount of space to be reserved
496 *
497 * Reserve an amount of space in the cache for the cache object attached to a
498 * cookie so that a write to that object within the space can always be
499 * honoured.
500 *
501 * See Documentation/filesystems/caching/netfs-api.txt for a complete
502 * description.
503 */
504 static inline
505 int fscache_reserve_space(struct fscache_cookie *cookie, loff_t size)
506 {
507 return -ENOBUFS;
508 }
509
510 /**
511 * fscache_read_or_alloc_page - Read a page from the cache or allocate a block
512 * in which to store it
513 * @cookie: The cookie representing the cache object
514 * @page: The netfs page to fill if possible
515 * @end_io_func: The callback to invoke when and if the page is filled
516 * @context: An arbitrary piece of data to pass on to end_io_func()
517 * @gfp: The conditions under which memory allocation should be made
518 *
519 * Read a page from the cache, or if that's not possible make a potential
520 * one-block reservation in the cache into which the page may be stored once
521 * fetched from the server.
522 *
523 * If the page is not backed by the cache object, or if it there's some reason
524 * it can't be, -ENOBUFS will be returned and nothing more will be done for
525 * that page.
526 *
527 * Else, if that page is backed by the cache, a read will be initiated directly
528 * to the netfs's page and 0 will be returned by this function. The
529 * end_io_func() callback will be invoked when the operation terminates on a
530 * completion or failure. Note that the callback may be invoked before the
531 * return.
532 *
533 * Else, if the page is unbacked, -ENODATA is returned and a block may have
534 * been allocated in the cache.
535 *
536 * See Documentation/filesystems/caching/netfs-api.txt for a complete
537 * description.
538 */
539 static inline
540 int fscache_read_or_alloc_page(struct fscache_cookie *cookie,
541 struct page *page,
542 fscache_rw_complete_t end_io_func,
543 void *context,
544 gfp_t gfp)
545 {
546 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
547 return __fscache_read_or_alloc_page(cookie, page, end_io_func,
548 context, gfp);
549 else
550 return -ENOBUFS;
551 }
552
553 /**
554 * fscache_read_or_alloc_pages - Read pages from the cache and/or allocate
555 * blocks in which to store them
556 * @cookie: The cookie representing the cache object
557 * @mapping: The netfs inode mapping to which the pages will be attached
558 * @pages: A list of potential netfs pages to be filled
559 * @nr_pages: Number of pages to be read and/or allocated
560 * @end_io_func: The callback to invoke when and if each page is filled
561 * @context: An arbitrary piece of data to pass on to end_io_func()
562 * @gfp: The conditions under which memory allocation should be made
563 *
564 * Read a set of pages from the cache, or if that's not possible, attempt to
565 * make a potential one-block reservation for each page in the cache into which
566 * that page may be stored once fetched from the server.
567 *
568 * If some pages are not backed by the cache object, or if it there's some
569 * reason they can't be, -ENOBUFS will be returned and nothing more will be
570 * done for that pages.
571 *
572 * Else, if some of the pages are backed by the cache, a read will be initiated
573 * directly to the netfs's page and 0 will be returned by this function. The
574 * end_io_func() callback will be invoked when the operation terminates on a
575 * completion or failure. Note that the callback may be invoked before the
576 * return.
577 *
578 * Else, if a page is unbacked, -ENODATA is returned and a block may have
579 * been allocated in the cache.
580 *
581 * Because the function may want to return all of -ENOBUFS, -ENODATA and 0 in
582 * regard to different pages, the return values are prioritised in that order.
583 * Any pages submitted for reading are removed from the pages list.
584 *
585 * See Documentation/filesystems/caching/netfs-api.txt for a complete
586 * description.
587 */
588 static inline
589 int fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
590 struct address_space *mapping,
591 struct list_head *pages,
592 unsigned *nr_pages,
593 fscache_rw_complete_t end_io_func,
594 void *context,
595 gfp_t gfp)
596 {
597 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
598 return __fscache_read_or_alloc_pages(cookie, mapping, pages,
599 nr_pages, end_io_func,
600 context, gfp);
601 else
602 return -ENOBUFS;
603 }
604
605 /**
606 * fscache_alloc_page - Allocate a block in which to store a page
607 * @cookie: The cookie representing the cache object
608 * @page: The netfs page to allocate a page for
609 * @gfp: The conditions under which memory allocation should be made
610 *
611 * Request Allocation a block in the cache in which to store a netfs page
612 * without retrieving any contents from the cache.
613 *
614 * If the page is not backed by a file then -ENOBUFS will be returned and
615 * nothing more will be done, and no reservation will be made.
616 *
617 * Else, a block will be allocated if one wasn't already, and 0 will be
618 * returned
619 *
620 * See Documentation/filesystems/caching/netfs-api.txt for a complete
621 * description.
622 */
623 static inline
624 int fscache_alloc_page(struct fscache_cookie *cookie,
625 struct page *page,
626 gfp_t gfp)
627 {
628 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
629 return __fscache_alloc_page(cookie, page, gfp);
630 else
631 return -ENOBUFS;
632 }
633
634 /**
635 * fscache_readpages_cancel - Cancel read/alloc on pages
636 * @cookie: The cookie representing the inode's cache object.
637 * @pages: The netfs pages that we canceled write on in readpages()
638 *
639 * Uncache/unreserve the pages reserved earlier in readpages() via
640 * fscache_readpages_or_alloc() and similar. In most successful caches in
641 * readpages() this doesn't do anything. In cases when the underlying netfs's
642 * readahead failed we need to clean up the pagelist (unmark and uncache).
643 *
644 * This function may sleep as it may have to clean up disk state.
645 */
646 static inline
647 void fscache_readpages_cancel(struct fscache_cookie *cookie,
648 struct list_head *pages)
649 {
650 if (fscache_cookie_valid(cookie))
651 __fscache_readpages_cancel(cookie, pages);
652 }
653
654 /**
655 * fscache_write_page - Request storage of a page in the cache
656 * @cookie: The cookie representing the cache object
657 * @page: The netfs page to store
658 * @object_size: Updated size of object
659 * @gfp: The conditions under which memory allocation should be made
660 *
661 * Request the contents of the netfs page be written into the cache. This
662 * request may be ignored if no cache block is currently allocated, in which
663 * case it will return -ENOBUFS.
664 *
665 * If a cache block was already allocated, a write will be initiated and 0 will
666 * be returned. The PG_fscache_write page bit is set immediately and will then
667 * be cleared at the completion of the write to indicate the success or failure
668 * of the operation. Note that the completion may happen before the return.
669 *
670 * See Documentation/filesystems/caching/netfs-api.txt for a complete
671 * description.
672 */
673 static inline
674 int fscache_write_page(struct fscache_cookie *cookie,
675 struct page *page,
676 loff_t object_size,
677 gfp_t gfp)
678 {
679 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
680 return __fscache_write_page(cookie, page, object_size, gfp);
681 else
682 return -ENOBUFS;
683 }
684
685 /**
686 * fscache_uncache_page - Indicate that caching is no longer required on a page
687 * @cookie: The cookie representing the cache object
688 * @page: The netfs page that was being cached.
689 *
690 * Tell the cache that we no longer want a page to be cached and that it should
691 * remove any knowledge of the netfs page it may have.
692 *
693 * Note that this cannot cancel any outstanding I/O operations between this
694 * page and the cache.
695 *
696 * See Documentation/filesystems/caching/netfs-api.txt for a complete
697 * description.
698 */
699 static inline
700 void fscache_uncache_page(struct fscache_cookie *cookie,
701 struct page *page)
702 {
703 if (fscache_cookie_valid(cookie))
704 __fscache_uncache_page(cookie, page);
705 }
706
707 /**
708 * fscache_check_page_write - Ask if a page is being writing to the cache
709 * @cookie: The cookie representing the cache object
710 * @page: The netfs page that is being cached.
711 *
712 * Ask the cache if a page is being written to the cache.
713 *
714 * See Documentation/filesystems/caching/netfs-api.txt for a complete
715 * description.
716 */
717 static inline
718 bool fscache_check_page_write(struct fscache_cookie *cookie,
719 struct page *page)
720 {
721 if (fscache_cookie_valid(cookie))
722 return __fscache_check_page_write(cookie, page);
723 return false;
724 }
725
726 /**
727 * fscache_wait_on_page_write - Wait for a page to complete writing to the cache
728 * @cookie: The cookie representing the cache object
729 * @page: The netfs page that is being cached.
730 *
731 * Ask the cache to wake us up when a page is no longer being written to the
732 * cache.
733 *
734 * See Documentation/filesystems/caching/netfs-api.txt for a complete
735 * description.
736 */
737 static inline
738 void fscache_wait_on_page_write(struct fscache_cookie *cookie,
739 struct page *page)
740 {
741 if (fscache_cookie_valid(cookie))
742 __fscache_wait_on_page_write(cookie, page);
743 }
744
745 /**
746 * fscache_maybe_release_page - Consider releasing a page, cancelling a store
747 * @cookie: The cookie representing the cache object
748 * @page: The netfs page that is being cached.
749 * @gfp: The gfp flags passed to releasepage()
750 *
751 * Consider releasing a page for the vmscan algorithm, on behalf of the netfs's
752 * releasepage() call. A storage request on the page may cancelled if it is
753 * not currently being processed.
754 *
755 * The function returns true if the page no longer has a storage request on it,
756 * and false if a storage request is left in place. If true is returned, the
757 * page will have been passed to fscache_uncache_page(). If false is returned
758 * the page cannot be freed yet.
759 */
760 static inline
761 bool fscache_maybe_release_page(struct fscache_cookie *cookie,
762 struct page *page,
763 gfp_t gfp)
764 {
765 if (fscache_cookie_valid(cookie) && PageFsCache(page))
766 return __fscache_maybe_release_page(cookie, page, gfp);
767 return true;
768 }
769
770 /**
771 * fscache_uncache_all_inode_pages - Uncache all an inode's pages
772 * @cookie: The cookie representing the inode's cache object.
773 * @inode: The inode to uncache pages from.
774 *
775 * Uncache all the pages in an inode that are marked PG_fscache, assuming them
776 * to be associated with the given cookie.
777 *
778 * This function may sleep. It will wait for pages that are being written out
779 * and will wait whilst the PG_fscache mark is removed by the cache.
780 */
781 static inline
782 void fscache_uncache_all_inode_pages(struct fscache_cookie *cookie,
783 struct inode *inode)
784 {
785 if (fscache_cookie_valid(cookie))
786 __fscache_uncache_all_inode_pages(cookie, inode);
787 }
788
789 /**
790 * fscache_disable_cookie - Disable a cookie
791 * @cookie: The cookie representing the cache object
792 * @aux_data: The updated auxiliary data for the cookie (may be NULL)
793 * @invalidate: Invalidate the backing object
794 *
795 * Disable a cookie from accepting further alloc, read, write, invalidate,
796 * update or acquire operations. Outstanding operations can still be waited
797 * upon and pages can still be uncached and the cookie relinquished.
798 *
799 * This will not return until all outstanding operations have completed.
800 *
801 * If @invalidate is set, then the backing object will be invalidated and
802 * detached, otherwise it will just be detached.
803 *
804 * If @aux_data is set, then auxiliary data will be updated from that.
805 */
806 static inline
807 void fscache_disable_cookie(struct fscache_cookie *cookie,
808 const void *aux_data,
809 bool invalidate)
810 {
811 if (fscache_cookie_valid(cookie) && fscache_cookie_enabled(cookie))
812 __fscache_disable_cookie(cookie, aux_data, invalidate);
813 }
814
815 /**
816 * fscache_enable_cookie - Reenable a cookie
817 * @cookie: The cookie representing the cache object
818 * @aux_data: The updated auxiliary data for the cookie (may be NULL)
819 * @object_size: Current size of object
820 * @can_enable: A function to permit enablement once lock is held
821 * @data: Data for can_enable()
822 *
823 * Reenable a previously disabled cookie, allowing it to accept further alloc,
824 * read, write, invalidate, update or acquire operations. An attempt will be
825 * made to immediately reattach the cookie to a backing object. If @aux_data
826 * is set, the auxiliary data attached to the cookie will be updated.
827 *
828 * The can_enable() function is called (if not NULL) once the enablement lock
829 * is held to rule on whether enablement is still permitted to go ahead.
830 */
831 static inline
832 void fscache_enable_cookie(struct fscache_cookie *cookie,
833 const void *aux_data,
834 loff_t object_size,
835 bool (*can_enable)(void *data),
836 void *data)
837 {
838 if (fscache_cookie_valid(cookie) && !fscache_cookie_enabled(cookie))
839 __fscache_enable_cookie(cookie, aux_data, object_size,
840 can_enable, data);
841 }
842
843 #endif /* _LINUX_FSCACHE_H */